Device for withdrawing a catheter

ABSTRACT

A device is disclosed for withdrawing a catheter or a probe from a body cavity or a body vessel with a drive which preferably is a friction drive and engages the axially movable part of the catheter. The drive is formed by at least one roller which is mounted for rotation around a shaft extending transversely to the direction of pull, which roller cooperates with at least one spring-loaded counter-roller, the rollers enclosing the catheter or the probe, with at least one roller being connected to a driving motor.

This application is a national phase application based uponcorresponding PCT application PCT/EP98/00151 filed on Jan. 9, 1998 (WO98/30266), which is in turn based upon Austrian application GM 14/97filed on Jan. 9, 1997 from which priority is claimed.

FIELD OF THE INVENTION

The invention relates to a device for withdrawing a catheter or a probefrom a body cavity or a body vessel, with a drive which is preferably afriction drive and engages the axially movable part of the catheter.

BACKGROUND OF THE INVENTION

Catheters or probes are increasingly used in invasive medicine. Suchcatheters or probes enable body cavities or the vascular system to beanalyzed or treated, e.g. intravascular ultrasonic probes being used indiagnostic medicine. While classical angiography only enables changes inlongitudinal section and in particular stenoses in blood vessels to beidentified, information about the condition of vascular walls can besuccessfully obtained with such intravascular ultrasonic catheters. Inparticular, information about calcification, lipoid or fibroticstructures of vascular walls can be obtained with such intravascularultrasonic catheters, which information in particular serves as a checkfollowing interventions, such as, e.g., a stent implantation, todetermine whether there are vascular wall injuries or not. Besidesintravascular ultrasonic catheters, in which at least one piezoelectriccrystal is arranged at the probe head to obtain an image, probes havealready been used for treatment, such as, e.g., for intravascularradiation. When a so-called imaging catheter is equipped with only onecrystal to obtain an image of the internal wall of a vessel, it isrequired for completely imaging the vascular wall to rotate thiscatheter about its axis during withdrawal, so that the image can beobtained as a spirally developed view of the vascular wall. Besides aregulated or constant number of revolutions, a regulated or constantspeed during withdrawal of the catheter is a prerequisite. Besides suchrotatably driven imaging catheters, there are also known structureshaving a plurality of crystals which are scanned in a correspondingphase. In such so-called “phased array” catheters, the rotation of thecatheter can be omitted. However, an unavoidable prerequisite for areproducible evaluation of the images is again a defined, in particularconstant driving speed during withdrawal of the catheter. Forintravascular radiations, too, a uniform feed is essential for the exactdosage. Moreover, during the uniform feed a concentration or iongradient can be determined in vessels and organs.

The hitherto known devices for withdrawing catheters are relativelyheavy and large. In rotating intravascular ultrasonic catheters theheavy motor required for rotational drive is then placed in acorresponding holding device and moved in the longitudinal direction ofthe catheter together with the axially movable part of the catheter. Atthe operating table there is hardly any room for such large and heavydevices, so that their handling is relatively laborious. Moreover, suchdevices usually cannot be sterilized without additional measures, and itis therefore necessary to use them in a corresponding sterile package,which further complicates their handling. Moreover, these known heavyand large devices are very expensive and usually can only be used inconnection with a specific drive, e.g. for an intravascular ultrasoniccatheter.

NL 10 00 685 C2 shows and describes a device for the controlled movementof a catheter, which comprises a resilient frame open on one side, inwhich a driving device connected with one end of the frame, such as,e.g., an arm or a pinion, cooperates with the catheter passed intoopenings in the frame. The frame is compressed manually, with thecatheter being moved through the driving device. An adjusting screwenables the compression to be limited and thus a defined stroke and adefined path of movement of the catheter to be adjusted. Additionally,electric contacts are provided at the frame, with which a signalcorresponding to the movement of the catheter can be produced during thecompression of the frame.

U.S. Pat. No. 4,233,991 A shows and describes a device for withdrawing aurethral catheter, which comprises withdrawing the catheter through aspindle drive connected to a motor. The catheter is connected to thespindle drive via clamping devices.

SUMMARY OF THE INVENTION

The object of the invention is to provide a small and multi-purposedevice for withdrawing a catheter, which enables different catheters tobe safely driven for different purposes in the same way so as towithdraw the catheter. Besides very small sizes, the device according tothe invention must also enable a correspondingly simple handling and beadaptable to different catheters or probes without extensiveadaptations. To achieve this object, the device according to theinvention essentially consists in that the drive comprises at least onemember, which is mounted on a shaft or the like extending transverselyto the direction of pull, which member cooperates with at least acounter-member, such that in operation the catheter or probe is heldbetween said members, and that said at least one member is connected toa driving means for actuating said at least one member. In a preferredembodiment of the device according to the invention the drive is formedby at least one roller which is mounted for rotation around a shaftextending transversely to the direction of pull, which roller cooperateswith at least one spring-loaded counter-roller, the rollers enclosingthe catheter or the probe, and the at least one roller is connected to adriving motor. Owing to the fact that a friction drive is used, in whichthe withdrawable part of the catheter or the probe is gripped andconveyed between at least two rotating rollers, a substantially shorterand smaller device can be used for any path of movement when withdrawinga catheter or a probe, while the separate simultaneous rotationalmovement of such a withdrawing part is not adversely affected. Owing tothe fact that one of the rollers is pressed in a spring-loaded fashionagainst at least one driven roller, the feeding or withdrawing movementof the catheter can be controlled in a very exact manner, while also thedriving motor and, if required, the energy supply can be accommodated inthe correspondingly small device. In principle, this drive can also be acrawler drive or, e.g., a drive with a driven roller which cooperateswith two spring-loaded rollers, so as to obtain as gentle a frictionengagement as possible, with a high transmission of pull.

The structure is advantageously of such a type that the driving motor isconnected to the roller or rollers via a driving gear. Thus therequirements can be met with very small driving motors which rotate at acorrespondingly higher number of revolutions, while the force requiredfor withdrawing the catheter is guaranteed by the gear reduction.

The object of providing a small device is guaranteed in a verysimple,manner in that the axis of the driving motor is arrangedsubstantially parallel to the direction of pull in a housing carryingthe rollers and that the roller or rollers is or are driven via aspindle drive with a shaft crossing the axis or axes of the roller orrollers. In such a structure the total drive for withdrawing a catheteror a probe can be accommodated in a very small housing, which device, inview of its simple structure, can be formed as a disposable device atcorrespondingly low cost. For repeated use of the same drive, asterilization should be effected. The use of a spindle drive alsopermits the arrangement of a very small driving gear. In a a smallhousing several transmission steps can be provided between the drivingmotor and the spindle, so that a correspondingly large gear reductioncan be achieved between the motor and the driving spindle, as a resultof which the normally desired linear driving speed can be exactlymaintained between 0.25 and 1 mm/sec.

In view of the small sizes the structure can advantageously be of such atype that the driving motor is connected to a power source disposed inthe housing, which power source may be, e.g., a battery or anaccumulator. The battery or accumulator may be arranged in a handlewhich can be connected to the housing with the drive for the movablepart of the catheter or the probe.

The rate of feed or the rate of withdrawal can be adjusted in a verysimple manner such that the driving motor is connected to the powersource via a step switch arranged in the housing.

To further facilitate the handling of the device, the structure isadvantageously of such a type that the housing has a swing cover, inwhich at least one roller or grabjaw is mounted. In such a structure thehousing must only be swung open and the withdrawable part of thecatheter or the probe is placed on one of the rollers or grabjaws,following which the desired pressure for the friction drive is obtaineddirectly after closing of the housing. The stationary part, such as,e.g., the catheter casing, can preferably be supported on an abutment ofthe housing. The structure is preferably of such a type that the housinghas a channel crossing the drive for receiving the catheter or theprobe. In addition to such a channel, into which the opposite rollers,grabs or like means enter, a further parallel channel for fixing afurther catheter or other stationary parts of the catheter can beprovided, while the total device can be arranged in any place withoutseparate fixing. In view of the small sizes and low cost, the drive canalso directly integrate into the catheter, which may further facilitatethe handling. Besides electromagnetic motors, piezoelectricmagnetostrictive motors or spring motors can be advantageously used. Anultrasonic motor can also be arranged directly in or at a roller. Afteropening the housing, a rapid return movement of the catheter is madepossible, while the motor control can be preset in any manner. Besidespreferably at least two speeds different from each other, the control ofthe motor can be made dependent on a series of further measuringparameters, with which, e.g., contractions of muscles, e.g. the pulsebeat, can be considered. The length over which the catheter must bewithdrawn can be simply limited over the switching time of the motor,which is particularly advantageous for the local limitation of thedesired image recording. To ensure that the desired feed was actuallyobtained within the given time and to check or regulate the function ofthe friction drive, the structure is preferably of such a type that arecording device is provided for, in particular optical or magnetic,markings, arranged at the axially movable part of the catheter, formonitoring or regulating the drive. In view of the very small structure,a sterilization of the device can also be obtained in a substantiallysimpler manner than in the known devices. The device according to theinvention can be adapted to different catheters without additionalcomponent parts, because it suffices to support the enveloping tube onan abutment of the housing.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will hereinafter be explained in more detail withreference to a practical example diagrammatically shown in the drawings.In these drawings FIG. 1 shows a front view of an embodiment of thedevice according to the invention, partly in cross-section, and FIG. 2shows a side view of the device shown in FIG. 1, likewise partly incross-section.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a housing 1, the cover 2 of which is hinged to the lowerpart 4 of the housing on a hinge 3. Formed between the cover 2 and thelower part 4 of the housing is a channel 5, in which the withdrawablepart of the catheter or the probe is placed. Cooperating with the partplaced in this channel 5 are two rollers 6 and 7, of which the roller 6,which is mounted for rotation in the lower part 4 of the housing, isconnected to a drive derived from a spindle 8. The rollers 6 and 7 aremounted for rotation around shafts 9 and 10, each orthogonally crossingthe axis of the channel 5. In the chosen structure, only one of therollers 6 are driven, with the spindle 8 meshing with a pinion 11, whichis connected to the roller so as to be secured against rotation. Theopposite roller 7 is pressed via springs 12 against the part of thecatheter received in the channel 5. Besides this channel 5, there may beprovided further parallel channels, not shown, for catheters to bestationarily held. The withdrawable part of the catheter is then placedby swinging open the cover 2 around the pivot pin of the hinge 3, afterwhich the pressure required for the friction drive between the rollers 6and 7 is obtained directly after closing.

In FIG. 2, the reference numerals of FIG. 1 were maintained. Moreover,it can be seen that the driving motor 14 is arranged in the lower part 4of the housing parallel to the axis 13 of the channel 5. This drivingmotor is connected to the spindle 8 via a multi-step reduction gear 15.The driving motor 14 is an electric motor and is connected to a battery,not shown, which is arranged, e.g., in a handle portion for the lowerpart 4 of the housing. The handle portion may also contain the switch,not shown, in particular the multi-step reduction gear for adjustingdifferent speeds as well as a corresponding electronic device whichcontrols the feed or withdrawal of the movable part of the catheter.Provided at the inlet end 16 for the catheter is an abutment 17 forsupporting the stationary part of the catheter, thus enabling the use ofcatheters of different sizes or adaptations.

What is claimed is:
 1. A system for withdrawing a catheter from a body,the system comprising: a catheter; a device for withdrawing the catheterfrom the body comprising: a housing; and a friction drive engaging anaxially movable part of the catheter, wherein the friction drivecomprises: at least one roller mounted for rotation around a shaftextending transversely to a direction of pull, the roller being drivenby a driving motor, for at least withdrawing the catheter at acontrolled speed over a portion of the body, and at least onespring-loaded counter-roller, which cooperates with the at least oneroller to engage at least the catheter.
 2. A system according to claim1, wherein the diving motor is connected to the at least one roller viaa driving gear.
 3. A system according to claim 1, wherein the axis ofthe driving motor is arranged substantially parallel to the direction ofpull in the housing carrying the rollers, and that the at least oneroller is driven via a spindle drive with a shaft crossing the axis ofthe at least one roller.
 4. A system according to claim 1, wherein thedriving motor is connected to a power source arranged in the housing. 5.A system according to claim 4, wherein the driving motor is connected tothe power source via a step switch arranged in the housing.
 6. A systemaccording to claim 5, wherein the housing further comprises a swingcover, in which the at least one counter-roller is mounted.
 7. A systemaccording to claim 6, in the housing further comprises a channelcrossing the friction drive for receiving at least the catheter.
 8. Asystem according to claim 7, further comprising: an abutment of thehousing, arranged for supporting a stationary part of the catheter.
 9. Asystem according to claim 8, further comprising: a recording device formonitoring and regulating the friction drive, the recording device, whenin operation, being responsive to markings arranged at the axiallymovable part of the catheter.
 10. A system for withdrawing a catheterfrom a body, the system comprising: a catheter; a device for withdrawingthe catheter from the body comprising: a drive engaging an axiallymovable part of at least the catheter, wherein the drive comprises: atleast one member mounted on a shaft extending transversely to adirection of pull that is connected to a driving means for actuating theat least one member; at least a spring loaded counter-roller, whichcooperates with the at least one member such that at least the catheteris held between the members; and an axis of the driving means arrangedsubstantially parallel to the direction of pull for withdrawing at leastthe catheter at a controlled speed over at least a portion of the body.11. A device for withdrawing a catheter from a body, the devicecomprising: a housing including an opening allowing passage of acatheter into the device; and a friction drive means for engaging anaxially movable part of the catheter, wherein the friction drive meanscomprises; at least one roller mounted for rotation around a shaftextending transversely to a direction of pull, the roller being drivenby a driving motor, for at least withdrawing the catheter at acontrolled speed over a portion of the body, and at least onespring-loaded counter-roller, which cooperates with the at least oneroller to engage at least the catheter.
 12. A device according to claim11, wherein the driving motor is connected to the at least one rollervia a driving gear.
 13. A device according to claim 11, the drivingmotor having an axis, wherein the axis of the driving motor is arrangedsubstantially parallel to the direction of pull in the housing carryingthe rollers, and that the at least one roller is driven via a spindledrive with a shaft crossing the axis of the at least one roller.
 14. Adevice according to claim 11, wherein the driving motor is connected toa power source arranged in the housing.
 15. A device according to claim14, wherein the driving motor is connected to the power source via astep switch arranged in the housing.
 16. A device according to claim 15,wherein the housing further comprises a swing cover, in which the atleast one counter-roller is mounted.
 17. A device according to claim 16,wherein the housing further comprises a channel crossing the frictiondrive for receiving at least the catheter.
 18. A device according toclaim 17, further comprising: an abutment of the housing for supportinga stationary part of the catheter.
 19. A device according to claim 18,further comprising: a recording device for monitoring and regulating thefriction driving means, the recording device, when in operation, beingresponsive to markings arranged at the axially movable part of thecatheter.
 20. A device for withdrawing a catheter from a body, thedevice comprising: a friction drive means for engaging an axiallymovable part of at least the catheter, wherein the friction drive meanscomprises: at least one member means mounted on a shaft extendingtransversely to a direction of pull that is connected to a driving meansfor actuating the at least one member; at least one counter-membermeans, which cooperates with the at least one member means such that atleast the catheter is held between the members means; and an axis of thedriving means arranged substantially parallel to the direction of pullfor withdrawing at least the catheter at a controlled speed over atleast a portion of the body.